Didnt have any read on V, probs was playing to many tables

So I was barrelling so I have options on the river as we hold the NFD blocker, when he check raises, you ever calling, seems weird?!

iPoker - €0.20 PL Hi (6 max) - Omaha Hi - 6 players
Hand converted by PokerTracker 4

SB: 199.2 BB (VPIP: 54.00, PFR: 26.00, 3Bet Preflop: 15.38, Hands: 52)
BB: 100 BB (VPIP: 34.78, PFR: 8.70, 3Bet Preflop: 0.00, Hands: 24)
UTG: 106.7 BB (VPIP: 37.71, PFR: 25.25, 3Bet Preflop: 8.62, Hands: 299)
MP: 99 BB (VPIP: 45.45, PFR: 9.09, 3Bet Preflop: 0.00, Hands: 11)
Hero (CO): 170.05 BB
BTN: 53.9 BB (VPIP: 61.79, PFR: 32.52, 3Bet Preflop: 8.16, Hands: 127)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 4 A Q 5

fold, fold, Hero raises to 3 BB, fold, fold, BB calls 2 BB

Flop: (6.5 BB, 2 players) 4 K 3
BB checks, Hero bets 4.55 BB, BB calls 4.55 BB

Turn: (15.6 BB, 2 players) A
BB checks, Hero bets 10.9 BB, BB calls 10.9 BB

River: (37.4 BB, 2 players) 8
BB checks, Hero bets 26.15 BB, BB raises to 81.55 BB and is all-in, Hero ??

It's for sure a weird line by BB, but given that it's PLO 20, there's always a chance he turned a T-high flush and thinks he has the nuts and is c/s river for lol value.

But generally, I would fold. Villain called pre, flop and turn bets, so he has to have something. And villains never c/s river in this spot with just a single pair. That means that he has a hand, so if he doesn't have the flush he probably has a hand that beats us anyways.

Bet turn and river bigger. Or check back turn and decide whether you want to bluffcatch (or bluffraise) river.
Against your line I might shove Jhigh flush for value, which is what villain might be doing. I also cant think of what he can be turning into a bluff here, so I dont think we can call.

Second person to mention my sizing today! Something I need to look at. This line to me looks more value bet than bluff to me, but I guess this is how I size value bets.

So if we're barrel nut flush blocker and consequently nut flush, we should betting near pot??

I think that's theoretically correct and most regs do that, yes.

Fold river.

Check down turn+river imo. As played fold river.

Size bigger, fold river.